Engine starting apparatus



May 21, 1946.

lll IIII Il Illllllll H. `A. THORNBURG ENGINE STARTING APPARATUS 2 sheets-sheet '1 May `21, 1946.'` H, A. TAORNBURG "2,400,789,

ENGINE STARTING APPARATUS Filed May` 2G, 1943 2 Sheets-Sheet l12 Patented May 21, 1946 i l y 2,400,789f`,

UNITED STATES PATENT OFFICE 2,400,789 ENGINE STARTING APPARATUS Herbal A. Thornburg, Anderson, Ind., assigner to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application May 26. 1943, Serial No. 488,595 4 claims. (ci. 74491) I'his invention relates to engine starters for a disc 5| fixed to a rod 52 and the hub 53. of a heavy duty requiring the use of a torque limiting driving element 54 adapted by axial movement to means to prevent straining abnormally the mechengage with a similar driven element (not shown) anism which connects the starting motor shaft connected with the engine to be started. A spring with the engine. 6 55 urges element 54 away from disc 5| until ele- It is an object of the invention to provide a ment 54 strikes a nut 56 threaded on the end of torque limiting device which can be produced rod 52, thus limiting separation of disc and at relatively low cost and which can be easily element 54. Element 54 is normally held out of adjusted from the exterior of the starting appaengagement with the driven element on the enratus. According to the embodiment of the in-l 10 gine by a spring 51 located between the rotatable vention herein disclosed, this object is accomframe 4| and thimble 58 attached to the left plished through the use of a planetary speed reend of rod 52. When the rod 52 is moved right ducing drive having a ring gear which is fricby means to be described later, the disc 5| moves tionally connected with stationary parts by a right and movement to the right is transmitted restraining means comprising a plurality of by spring 55 from the disc 5| to the driving eleplates which are urged together by coiled springs, ment 54.

the compression of which is adjusted by screws The hub 38 of internal gear disc 31 provides having their heads located on the exterior of the a gear 60 meshing with four gears 6| (Fig. 3) starter housing. By turning the screws the fricwhich support the outer races of ball bearings 62,

tion pressure can be so adjusted that the ring the inner races of which are supported by plugs gear will slip when the torque exceeds a safe 63 carried by the rotating frame 4I. A ring 65 i value. In this way the shock incidental to the is secured to frame 4| by screws 64 extending connecting of the starting motor, while operating, through the plugs 63,' and at points between the with the engine is reduced. plugs 63, as indicated in Figs. 1 and 3, other Further objects and advantages of the present screws 66 pass through spacers 61, positioned invention will be apparent from the following debetween the ring and frame 4|, the 4screws 66 scription, reference being had to the accompanydirectly engaging the frame 4|. Gears 6| mesh ing drawings wherein a preferred embodiment of with an internal ring gear 10, the teeth of which the present ,invention is clearly shown. have projections 1| received by holes in the plates In the drawings: 12. The body of gear 10 is confined between Fig. 1 is a longitudinal sectional view of an the plates 13, and these are held against rotaengine starter embodying the present invention. Ation by the adjusting screws 11 described more Fig. 2 is a composite view in four parts marked fully later, which extend through holes in the 2A, 2B, 2C, 2D respectively. Part 2A is a fragplates 13. The right hand plate 12 is confined mentary endview taken in the direction of arrow between a plate 13 and a plate 14 bearing against 2A of Fig. l. Parts 2B, 2C and 2D are fragmena plane surface of the housing 26. The left hand tary sectional views taken, respectively,.on lines plate 12 is conned between a plate 13 and a pres- 2B2B, 2C-2C, and 2D-2D of Fig. 1. sure ring 15. Scews 11 having head 18 located FIE- 3 1S a Sectionall Velvf'n lli; 3-3 gi", Fig. 1. outside the housing 26 pass through resilient lock Referring to Fig. a e en rame is at- 4o washer plates 19, the housing 2B, a plate 14, a tached by screws 2| to a iield frame 22 to which plate 13, a Spacer ring 15, a plate 13, the presrve ceaaghgonrale asrlr: sure ring 15 and springs 80 and screw-theadedly rin l hich serves as nut for all and 24 support ball bearings 21 and 28 journalling egasgrea'vs -a 'gie pressures exrted by the a motor Shaft 29 carrymg an armature 3 and a 45 springs 80 to create friction between the several commutator 3| engaged by brushes not shown.

. plates are adiusted by turning the screws 11 in 'I'he shaft 29 drives a gear 35 meshing with an order to limit to a safe value the torque trans internal gear 36 provided by a disc 31 having a itt d b h t, t t th n 1 hub 38 supporting a bearing bushing 39 jourm e y t e Stfar mg m0 or o e coup ng ee' nalled on the tubular extension 40 of a rotatable 50 ment 5.; frame 4| having flanges 42 and 43 supporting The ring gear 10 is received within a stationary inner races of ball bearings 44 and 45, the outer l rin? 01' annulus 76 through holes in Which the races of which are supported by gear housing 26. dlusting screws 11 extend. as shown in Fig. 2,

Frame 4| is internally splined at 50 to provide and screws 16a hold the annulus 16 against any driving connections between the trame 4| and 5 rotation so that the annulus will be properly positioned with respectto screws 11 and the latter can be adjusted without binding.

It will be noted that the adjusting screws 11 support the pressure springs 00, are adjustable to vary the pressure of ing means and also support and hold against rotation the ilxedplates of the 'restraining means.

In operation, when the motor is energized, the torque of the motor is transmitted through the previously described gearing and restraining mechanism to the driving element 5H. The gear is normally stationary and the planetary pinions 6| cooperate therewith in the usual manner to drive the element 6| and element 54 splined thereto. In the event, however, of any increased reactionV on the ring gear 10, the restraining means will yield and allow a movement of the ring gear to protect the parts of the starter assembly against injury.

The motor is controlled by a switch having two stationary contacts 90 and a bridging contact 9| insulatingly supported byra rod 92 attached to a solenoid armature 93 of a solenoid electro-magnet 96. Armature 93 slides within a tube 95 extending into a tube 91 enclosing a rod 96 attached to armature 93. Rod 96 is connected by a pin 98 with a link 99 having a slot |00 which receives a pin |0| connected with an arm |02 attached to a shaft |03 carrying an arm |04 for engaging the thimble 58.

When the solenoid 94 is energized by closing a control switch, not shown, the armature 93 moves left to move the switch contact 9| into engagement with contacts 90 and the rod 52 and the spring 55 move toward the right to force the coupling driving element 54 into engagement with its companion driven element, not shown. If complete engagement of the coupling elements does not occur before the motor starts the armature 93 continues to move left to close the motor switch. The motor starts and the coupling element 54 is rotated into full registration with its companion element. Before the complete engagement of the coupling elements takes place, the motor may attain considerable speed. The shock on the gearing incidental to starting the engine into motion is materially reduced by allowing the ring gear 10 to slip thus limiting the torque which can be transmitted to a value which will not abnormally strain the starting mechanism. As the speed of rotation of the engine crank shaft increases the torque decreases: and, the slippage of the ring gear 10 diminishes to zero before the engine becomes self-operative.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form,

it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

l. In engine starting apparatus having an electric motor provided with a frame, a gear housing attached thereto and a driving element operable by the motor and adapted t0 engage a driven element; means for connecting the motor with the driving element including planetary gearing within the housing and a relatively xed ring gear, a frictionplate restraining means for yieldably connecting the ring gear with the houssuch springs on the restrain-- ing and including, as rotatable plates, the ring gear and two other plates connected with the ring gear and spaced therefromand including, as ilxed plates, plates which engage the ring gear and .the rotatable plates connected with the ring gear, springs for applying pressure to the plates, and means including screws having heads located exterior to the housing for varying the pressure applied by the springs in order to variably limit the torque. y A

2. In engine starting apparatus having an electric motor provided with a frame, a gear housing attached thereto and a driving element operable by the motor and adapted to engage a driven element; means for connecting the motor with the driving element including planetary gearing within the housing and a relatively fixed ring gear, a friction plate restraining means for yieldably connecting the ring gear with the housing and including, as rotatable plates, the ring gear and two other plates spaced from the ring gear and connected with the ring gear through its gear teeth and including as xed plates, plates which engage the ring gear vand the rotatable plates connected with the ring gear, springs for applying pressure to the plates, and means including screws having heads located exterior to the housing for varying the pressure applied by the springs in order to variably limit the torque.

3. In engine starting apparatus having an electric motor provided with al frame, a gear housing attached thereto and a` driving element operable by the motor and adapted to engage a driven element; means for connecting the motor with the driving velement including planetary gearing within the housing and a relatively iixed ring gear, a friction plate restraining means for yieldably connecting the ring gear with the housing and including, as rotatable plates, the ring gear and two other plates connected with the ring gear and spaced therefrom and including, as fixed plates, plates which engage the ring gear and the rotatable plates connected with the ring gear, screws having heads located outside the housing and having their shanks passing through the housing and xed plates and having screw-threaded ends, a ring having tapped holes for receiving the screw-threaded ends of the screws, and coiled springs surrounding the screws and located between said ring and the nearest adjacent iixed plate of the restraining means.

4. In an engine starting apparatus having an electric motor provided with a frame, a gear housing attached thereto and a driving element operable by the motor and engaging a driven element; means for connecting the motor with the driving element including planetary gearing within the housing and a relatively xed ring gear, a friction plate restraining means for yieldably connecting the ring gear with the housing and including fixed and rotatable plates, springs for applying pressure to the plates and means for supporting said springs which is adjustable to vary the pressure exerted by said springs on the plates, said means also servingto prevent any rotational movement of the xed plates of said restraining means.

HERBAL A; THORNBURG. 

